The present invention relates to a cutting insert for grooving and parting work-pieces. The insert is of the type comprising a shaft part having at least one cutting head thereon. An end surface is disposed at the front end of the cutting insert, and a rear end surface is disposed at the rear end of the cutting insert. The shaft part comprises a top side, a bottom side as well as two sides side surfaces extending between the same. The cutting head carries a cutting edge which is defined by the intersection between a chip side and a clearance side. The cutting edge has a circular shape and has mainly the same (constant) curvature up to the ends thereof, the chip side of the cutting head is provided with a first chip-forming device placed immediately inwards from the cutting edge. Such a cutting insert is also suitable for profiling and longitudinal turning.
In such machining (i.e., grooving, parting, profiling and longitudinal turning), the chip breaking and the chip forming are frequently of crucial importance for undisturbed production. Modern, high-production machine tools make great demands on a good chip release. Long, uncontrollable chips may easily cause operational shutdowns and make it necessary to scrap components. Therefore, chip control has to be given close attention and it controls, to a large extent, the design of the cutting tools.
A requirement that affects the design of the cutting tool is the requirement for diversification. A tool that may handle a number of different operations or very varying cutting conditions may replace a number of xe2x80x9cconventionalxe2x80x9d tools that are more limited. A tool having the initially mentioned properties is to a large economic advantage in the machining industry because of decreased time losses for tool exchanges and savings, which are the result of a smaller number of tools.
A cutting insert for grooving as well as the widening of grooves comprising a partly circular cutting edge and a chip side provided with a number of concave recesses which intersect each other and placed immediately inwards from the cutting edge is, for instance, known from Swedish Patent 454248 (corresponding to U.S. Pat. No. 4,844,668). In practice, it has turned out that the ability of said cutting insert to give good chip control in a large a number of turning operations irrespective of feeding direction and over a large span of different cutting depths is very limited. This limitation is particularly large in connection with a plunging operation, which frequently starts the operations that are concerned.
An additional cutting insert for grooving as well as the widening of grooves, which comprises two ridges and bumps, is for instance known from EP 0 775 544 (corresponding to U.S. Pat. No. 5,827,017). The rectangular shape of the cutting head makes it suitable for plunging and grooving but not for profiling.
An object of the present invention is to form a cutting insert in such a way that it may carry out a large a number of turning operations irrespective of whether the cutting insert is mounted axially or radially in relation to the workpiece.
Another object is to adapt the cutting insert for good chip control irrespective of feeding direction, cutting depth, cutting speed or the material of the workpiece.
An additional object of the invention is to form a cutting insert, which cuts easily particularly during the plunging step of an overall cutting operation.
These and other objectives have been attained by a cutting insert for grooving and profiling which comprises a shaft part and at least one cutting head. There is a front end surface at a front end of the cutting insert, and a rear end surface at a rear end of the cutting insert. The shaft part comprises a top side, a bottom side, and side surfaces extending between the top and bottom sides. The cutting head carries a cutting edge defined by an intersection between a chip side and a clearance side of the cutting head. The cutting edge has a circular shape and a substantially constant curvature between the opposite ends thereof. The chip side of the cutting head is provided with a first chip-forming device placed immediately inside the cutting edge. The chip side of the cutting head further has a second chip-forming device located symmetrically around a center line of the cutting insert. The second chip-forming device comprises a chip-breaking depression, and a ridge. The depression is disposed inside of the first chip-forming device, except for a tip portion of the depression which extends along the center line up to the cutting edge. The ridge borders a rear part of the chip-breaking depression.